The tall wood doors open to reveal the whole world — turned inside out (disconcertingly, at first), in glowing stained glass, 30 feet across — and you step onto the glass bridge spanning its center.

It's the Mapparium. When architect Chester Lindsay Churchill designed the Christian Science Publishing Society headquarters in the early 1930s, he gave it a magic heart. His inspiration: the 12-foot globe in the New York Daily News headquarters. But he topped that, designing a three-story-tall globe to symbolize the nearby Mother Church's international reach (via its press and the Christian Science Monitor).

The Mapparium opened in 1935, designed to be updated, but all the changes of World War II and the dissolution of European colonial empires scotched that. Instead it's a time capsule of bygone nations: French Indo-China, Yugoslavia, Belgian Congo, the mammoth Soviet Union.

"This is our earth," a recorded voice intones. "There is no place like it." The 608 glass panels framed in bronze glow from the outside, the serene ocean blue-green against red, green, and orange nations. The show's a bit schmaltzy, ending with television footage of NASA rockets. But the globe's majesty can still take your breath away, overwhelming you with color, humbling. Then you notice voices murmuring in your ear — because of the way the room's shape reflects whispers. In that moment before you figure it out, it can feel like you're hearing everything.